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Purging is the process of adding a substance to an open system or releasing it, to go from one concentration to another, be it moisture, oxygen, or product purity. Purging a system to an inert state will render it safe from combustion or explosion as long as the inert state is maintained by blanketing.
The two main situations encountered in purging a chemical process include:
- Start up, where equipment containing air is to be placed into service
- Shut down, where equipment containing combustible gas or vapor is to be withdrawn from service
In general, Linde recommends between 3 to 5 tank volume changes of cryogenic-purity grade inert gas in order to achieve a safe atmosphere. Generated inert gas, such as from a Linde membrane generator, will require an even longer purge time due to its lower purity. A Linde engineer can assist with the number of purge volumes needed to ensure a safe operating condition. |
